1. Field of the Invention
The present invention relates to apparatus suitable for regulating fluid flow. More particularly, this invention relates to a programmable pump/controller.
2. Description of the Prior Art
A compact pump is disclosed in United States patents of Servain et al. entitled "Pump Assembly With Integral Electronically Commutated Drive System" (U.S. Pat. No. 5,096,390) and "Integral Electronically Commutated Drive System" (U.S. Pat. No. 5,197,865). The device of those patents discloses a magnetically torque-coupled pump that includes a number of advantageous features. It offers the advantages of an integrated assembly in which the pump drive shaft is coextensive with the shaft of the rotor of the associated electrical drive motor. As such, and in contrast to pumps of the "direct drive" type, it does not require dynamic or motor bearing seals that are known to impose excessive frictional loading and thus reduce useful life through contamination and seal failure. Finally, the disclosed pump is desirably brushless, eliminating the need for a spring-biased contact that could otherwise act as a source of intermittent failure.
While offering compactness and freedom from bearing-induced friction, the integration of pump and motor requires structures dedicated to preventing damage to electronic components through the migration of fluid into areas left "unprotected" by the absence of such bearing seals. Pump complexity and cost is thereby increased through the multiplication of parts requiring assembly and maintenance which add potential sources of failure.
Pumps of the above-described type are employed in numerous systems and applications. Some useful applications are found in the fields of facilities management, process control and like technologies. A representative use for a pump of the above-described or similar type is illustrated in FIG. 1, a schematic view of a radiant heating system in which a flow of heated water is supplied to a panel 10 for controlling temperature within a building.
Referring to the prior art radiant heating system of FIG. 1, optimum operation for efficiency and economy of use requires that the flow throughout the closed system take into account multiple factors. While such factors may vary from one specific application to another, one advantageous protocol takes into account the temperature of water heated by means of a boiler 12 that circulates within the piping 14 of a primary heating circuit 16. A useful point for ascertaining temperature in the system of FIG. 1, and thereby locating an appropriate sensor, is adjacent the tee joint 18. Another critical point in the system of FIG. 1 lies at the tee joint 20 located at the interface between the primary heating circuit 16 and the piping 22 of a secondary heating circuit 24 that includes the radiant heating panel 10. A third sensor may be appropriately located outside the building for measuring ambient temperature.
Optimum efficiency within the above protocol requires continual consideration and review of the various sensor outputs. For example, it may be inefficient for any flow of heated fluid to occur from the primary heating circuit 16 into the secondary heating circuit 24 before the boiler 12 has sufficiently heated the fluid.
Conventionally, systems of the above type, as well as much more complex systems, are regulated by means of a constant-speed pump 26 that may act in conjunction with a calibrated venturi valve 27 for setting associated gate valves whereby the flow rate is adjustable to maintain a desired temperature. Such arrangements are quite expensive in terms of hardware as the cost of the calibrated venturi valve may be at least equal to that of a pump 26 such as the device of the above-referenced patents. Further, additional time and expense may be incurred in adjusting the venturi valve 27 for cooperature utilization with the pump 26.